1. Field
The present disclosure relates to a fuel cell.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) including an electrolyte membrane, an anode electrode, and a cathode electrode. The electrolyte membrane is a solid polymer ion-exchange membrane. The anode electrode is disposed on one side of the electrolyte membrane, and the cathode electrode is disposed on the other side of the electrolyte membrane. The MEA and separators, sandwiching the MEA therebetween, constitute a power generation cell. A fuel cell stack is formed by stacking a predetermined number of such power generation cells, and the fuel cell stack is used, for example, as an automobile fuel cell stack installed in a fuel cell electric automobile.
In a fuel cell, it is necessary to gas-tightly hold a fuel gas and an oxidant gas in order to prevent a gas leak and the like and it is necessary to liquid-tightly hold a coolant in order to maintain a cooling function. For this purpose, various sealing structures are used.
For example, Japanese Unexamined Patent Application Publication No. 2007-42510 discloses a gasket for a fuel cell. The gasket includes a planar portion and a protruding portion, which stands on the planar portion and has a width smaller than that of the planar portion. At curved portions and branched portions of the gasket, the structure of an outer peripheral part of the protruding portion and the structure of an inner peripheral part of the protruding portion differ from each other.
The inner peripheral part is structured so that it can be deformed with a stress concentration smaller than that for deforming the outer peripheral part. It is described that, with such a structure, stress concentration on the curved portions and the branched portions can be suppressed when a fastening load or the like is applied to the gasket.
As illustrated in FIG. 5, for example, the gasket includes a planar portion 1a and a protruding portion 1b, which stands on the planar portion 1a and has a width smaller than that of the planar portion 1a. Excluding the curved portions and the branched portions of the gasket, the protruding portion 1b is symmetric about a center line 2 of the gasket in the width direction. In the curved portions and the branched portions of the gasket, the protruding portion 1b is asymmetric about the center line 2.
Regarding a gasket of this type, it is desirable to reduce the height h of the protruding portion 1b so that the size of the entirety of a fuel cell can be reduced.